Architectural Engineering of Nanowire Network Fine Pattern for 30 μm Wide Flexible Quantum Dot Light-Emitting Diode Application

Abstract

Replacing rigid metal oxides with flexible alternatives as a next-generation transparent conductor is important for flexible optoelectronic devices. Recently, nanowire networks have emerged as a new type of transparent conductor and have attracted wide attention because of their all-solution-based process manufacturing and excellent flexibility. However, the intrinsic percolation characteristics of the network determine that its fine pattern behavior is very different from that of continuous films, which is a critical issue for their practical application in high-resolution devices. Herein, a simple optimization approach is proposed to address this issue through the architectural engineering of the nanowire network. The aligned and random silver nanowire networks are fabricated and compared in theory and experimentally. Remarkably, network performance can be notably improved with an aligned structure, which is helpful for external quantum efficiency and the luminance of quantum dot light-emitting diodes (QLEDs) when the network is applied as the bottom-transparent electrode. More importantly, the advantage introduced by network alignment is also of benefit to fine pattern performance, even when the pattern width is narrowed to 30 μm, which leads to improved luminescent properties and lower failure rates in fine QLED strip applications. This paradigm illuminates a strategy to optimize nanowire network based transparent conductors and can promote their practical application in high-definition flexible optoelectronic devices.

Transparent Conducting Electrodes for Quantum Dots Light Emitting Diodes

“…Fang et al [98] investigated the performance of different TCEs based on Ag nanowires. As shown in Figure 14a and b, they found that the aligned structure improved the electrooptical performance of patterned Ag nanowire networks.…”

“…[1][2][3][4][5] Since the first demonstration of them, [6] there have been rapid advances in QDLED performance and fabrication processes, comparable with that of current LCDs and OLEDs. Blue, green, and red QDLEDs have demonstrated peak external quantum efficiency (EQE) of 12,16.5, and 20 %, respectively. [7][8][9] Among several layers and components in QDLEDs, electrical, optical, and morphological properties of transparent conducting electrodes (TCEs) critically influence their performance and reliability, including that of flexible QDLEDs.…”

“…To solve this problems, several alternatives such amorphous oxide electrodes, metal grid (mesh), metal nanowire, metal network, carbon nanotube (CNT), graphene, graphene oxide, conducting polymer, and hybrid electrodes have been extensively reported. [10][11][12][13][14][15][16][17][18] In fabricating QDLEDs, several new TCE materials have been employed as anodes or cathodes for hole/ electron injection. With this review, we report on recent research developments in TCEs for QDLEDs.…”

High‐Resolution Inkjet Printing of Quantum Dot Light‐Emitting Microdiode Arrays

“…Micro‐LED displays bring the stability and brightness of inorganic semiconductors to higher‐resolution displays, but the necessity of handling microscale semiconductor components implies fabrication challenges and limits flexibility in display design. An alternative route is the printing of quantum dot light‐emitting diodes (QLEDs) from particle dispersion: quantum dots (QDs) that individually emit light are deposited in suitable stacks in order to create displays . The QDs are composed of inorganic semiconductors and thus potentially more stable and brighter than organic semiconductors.…”

24.1% External Quantum Efficiency of Flexible Quantum Dot Light‐Emitting Diodes by Light Extraction of Silver Nanowire Transparent Electrodes

“…The brittle nature of ITO runs counter to good flexibility, and many efforts have been devoted to replace it with graphene, silver nanowires (AgNWs), and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) as flexible TCEs. On the other side, the refractive index of the commonly used plastic substrates (≈1.5) is much lower than ITO (1.8–2.1) in a standard substrate‐emitting architecture, which goes against effective light extraction into the viewing domain, and it will consume ≈40% and ≈20% of the total‐emitting light in the waveguide mode and substrate mode, respectively .…”